THE purpose of this report is to record the quantitative urinary excretion of glycocyamine, creatine and total creatinine by a group of normal infants and children.
The metabolism of creatinine is initiated in the renal epithelium where glycocyamine, or guanidoacetic acid, is synthesized from the two amino acids, glycine and arginine.1 Dubnoff and Borsook2 showed that in the normal adult 5 per cent of the glycocyamine is excreted in the urine and the remainder is transported to the liver, where it becomes the accepter of a methyl radical in the transmethylation process. Methionine and the system of choline and homocystine act as the methyl donors to form methylglycocyamine, or creatine. Most of the creatine is then converted to its anhydride, creatinine, and excreted as such in the urine, along with varying amounts of unconverted creatine.
As far as is known, this is the only course followed by glycocyamine
FLOOD RG, PINELLI RW. URINARY GLYCOCYAMINE, CREATINE AND CREATININEI. Their Excretion by Normal Infants and Children. Am J Dis Child. 1949;77(6):740-745. doi:10.1001/archpedi.1949.02030040755005